Am I correct in assuming that the shift knob uses right-hand thread? The 17mm jam nut loosened just fine, but the knob itself refuses to turn. --Colin
There's no trick ... once the jam nut is loosened, it should spin right off ... mine spun easily when I removed mine from my 355.
If yours is stuck, try wrapping rag around it and then use a large set of pliers to try and get it off.
Also auto parts stores have a wrench with an adjustable loop so there's no metal to metal contact. Also I would loosen the locking nut all the way and put a wrench to counter the force your using to remove the knob. Just as a precautionary measure so I wouldn't be putting so much pressure on the shift lever itself
You could try heating the knob up with a heat gun a little. It will loosen the thread a bit. If that doesn't work then wrap some ice cubes in a rag around the stick while doing it. Ideally use dry ice, but it is not always easy to find.
Like Randy said, go to Home Depot or Lowes into the plumbing section. For $7 you can get a rubber strap wrench (may be called a pipe wrench, or something like that) that will grip the knob and allow you to torque it without any risk of scratching. I wouldn't want to take a heat source into my interior to loosen the knob-- who knows what domino effect on some unrelated nearby thing that will trigger???
My dad also suggested a strap wrench, and this ultimately did work, but it fought him the whole way. After it was off, he ran a tap into the thread and this removed a non-trivial amount of material. Only then would the ball thread back on to the stick easily. It seems that the threads were cut slightly undersized at the factory. Maybe the tooling was past end-of-life when the shift ball was being made for this car?
Or it's more likely done deliberately so that the gear knob is guaranteed to be in the right position radially and tight enough so that it does not unscrew whilst driving, even if the knob is not fully tightened down! The last thing you want is to grab for a gear and have your hand slip off the gear knob because it's unscrewing during gear changes! Ask any woman - She'll tell you that a tight knob is much better than a loose knob!
That's why a jam nut is used against the bottom of the ball; the ball is threaded on so that the gear pattern is aligned, and then the jam nut holds it in place. The thread in the shift ball should not be tight.
As mentioned above ...... one of those rubber strap wrenches should do the trick .... I believe they are used for oil filters too.
